Researchers have identified the oldest known evidence of *Yersinia pestis*, the bacterium responsible for plague, in the remains of individuals from a Yamnaya culture site in Siberia. Dating back approximately 5,500 years, the discovery pushes back the known timeline of the plague’s emergence by over 2,000 years. Analysis of ancient DNA extracted from teeth revealed the presence of the plague bacterium in individuals buried at the site, suggesting a localized outbreak within the community. The Yamnaya culture was a late Copper Age/early Bronze Age pastoral nomadic culture that spread across the Eurasian Steppe. This finding challenges previous theories linking the plague’s origins to the Bronze Age collapse and suggests it existed much earlier, potentially spreading with migrations. The research provides new insights into the evolutionary history of *Y. pestis* and its impact on ancient populations. Further study of ancient genomes may reveal how the bacterium evolved and spread across Eurasia.